Comment 8 for bug 1791936

When assigning in reverse using only custom colors as you suggested (32 down to 1), it somewhat works, although not really (there are stray colors that are not changed at all).

When assigning even somewhat out of reverse order, colors revert back to what they were originally set to.

The colors still are not saved on exit.

Furthermore, launching from the terminal (gnome-system-monitor) reports no errors, and one warning:

Fontconfig warning: "/etc/fonts/conf.avail/53-monospace-lcd-filter.conf", line 10: Having multiple values in <test> isn't supported and may not work as expected